1. Field of the Invention
This invention relates generally to cargo containers, and more particularly concerns a cargo container for aircraft or seagoing vessels that has flexible, explosion resistant side walls and a flexible, explosion resistant door that are capable of expanding to substantially contain an explosive blast within the container.
2. Description of Related Art
Conventional cargo containers for aircraft and seagoing vessels are typically not constructed to resist and contain explosive blasts, making such containers vulnerable to deliberate bombings and accidental explosions of materials being transported in such containers. Cargo containers for seagoing vessels can be made of a heavier, sturdier construction in order to withstand internal explosions, but it is typically not practical or economical to use such heavy cargo containers in aircraft, for which weight reduction is an important consideration.
In one approach to making cargo containers explosion resistant, the cargo container is hardened, being formed of flat Kevlar and resin panels joined together along their peripheries. The corners are reinforced by making them of a greater thickness, and the construction provides many layers to withstand an explosion.
Another approach to providing a explosion resistant cargo container provides a strong lightweight double-walled reinforced vessel having an intermediate single woven member formed from Kevlar, graphite or fiberglass, and disposed between spaced apart first and second walls. The intermediate woven member comprises a plurality of longitudinally extending cylindrical members positioned parallel to each other and a plurality of generally parallel fibers woven about the cylindrical members and extending perpendicularly to the cylindrical members. The woven layer is bonded between the first inner wall and the second outer wall with resinous materials.
Another collapsible storage container for the transportation and storage of goods which otherwise could not be stably stacked is formed of all Kevlar or other materials. The container is formed of four walls hingedly connected together, the walls being formed by frames made from welded sections of rectangular hollow section steel with infill panels of a mesh such as Kevlar. A roof member is formed from a frame and a mesh infill panel in the same manner as each of the walls, and L-shaped brackets on the walls captively engage a pallet underneath the container.
Another known aircraft cargo container that is capable of expanding to facilitate containment of an explosive blast is formed of panels fastened together at the corners to form a container capable of expanding to facilitate containment of an explosive blast. The top and side panels are formed of knitted aramid material, and are joined to each other at edges and corners. The knitted aramid fibers are sandwiched between layers of foam material sandwiched between an inner skin comprising a fiberglass layer bonded to a sheet of PVF, PVC, or polyurethane, and an outer aluminum skin. The inner skin is a two-layer material of open weave glass fiber impregnated with a resin and bonded to a thin sheet of polyvinyl fluoride or the like. To enable the edges of the panel to be connected to other panels or the door frames of the container and to provide a secure anchorage for the Kevlar sheets, the outer aluminum skin is formed around its edges with one flange being securely connected to another similar flange of the comer joint extrusion by uniformly spaced rivets or bolts which also penetrate through all the other layers of the panel.
Another known explosion resistant cargo container is formed from a structural sandwich panel made of many layers of Kevlar. The sandwich panel is made of rigid structural face sheets and a hybrid core of rigid rod members which pierce and cross through layers of soft, dry, energy-absorbing material. The soft energy-absorbing material of the core can be made of several dry layers of woven ballistic fabric from aramid fibers such as Kevlar. Graphite epoxy yams are also sewn through the Kevlar fabric plies and the epoxy resin cured to rigidize the sewn cross-through members. The edges of the material were sewed and impregnated along the edges with epoxy resin for mounting in a frame.
It has however been found that while explosion resistant panels of various types can typically be made strong enough to contain an explosion, the seams along the frame where the panels are connected are typically the weakest point of the container in an explosion. There thus still exists a need a blast resistant cargo container with flexible, explosion resistant side walls for substantially containing the force of an explosion within the cargo container, that is relatively lightweight, with reinforcement of the seams along the frame where the panels are connected that are otherwise commonly the weakest point of the container during an explosion. The present invention meets these needs.
Briefly, and in general terms, the present invention provides for an improved, relatively lightweight explosion resistant cargo container having flexible, explosion resistant side walls for substantially containing the force of an explosion within the cargo container, the explosion resistant side walls having a unique edge assembly for reinforcing the seams of the explosion resistant side walls along the frame that are otherwise commonly the weakest point of the container during an explosion. In one preferred embodiment, the explosion resistant cargo container is made of a plurality of panels that are assembled with fasteners, and can be disassembled for shipping and repair. The panel construction allows for a simple repair, since a damaged panel can be replaced with a new panel by detaching the panel to be replaced, and attaching a replacement panel to the container. All of the panels are connected together so that a continuous explosion resistant container is formed on all sides of the container, including the door.
The invention accordingly provides for an explosion resistant cargo container suitable for aircraft or seagoing vessels for containing the effects of a bomb explosion within the cargo container, comprising a frame assembly, and a plurality of side walls including a bottom explosion resistant panel, a plurality of explosion resistant side walls, and an explosion resistant flexible door having two side edges and a bottom edge, the side panels and flexible door each being formed of one or more explosion resistant sheets of explosion resistant, flexible, high tensile strength material, the explosion resistant sheets having edges that are each wrapped around and secured to a mounting strip.
The frame preferably comprises a main section with two vertical front door post support members projecting from the bottom panel, a rear vertical side post support member projecting from the bottom panel, top transverse connector members connecting the vertical projecting support members, and flat gusset plates are provided for interconnecting at least some of the support members and transverse connector members of the support frame. The frame of the cargo container further typically comprises an angled projecting section, and the frame is comprised of a plurality of vertical support members and side transverse connector members.
In one presently preferred embodiment, each of the side walls are formed of individual explosion resistant side panels provided on the frame, along with a flexible door, with the edges of the explosion resistant sheets being connected by the unique edge assembly construction. While all of the panels are connected together so that a continuous explosion resistant container encompassing all sides and door of the container, this type of panel construction allows a damaged panel to be simply replaced with a new panel.
In another presently preferred embodiment, the frame is wrapped horizontally with one or more explosion resistant sheets to form a plurality of the explosion resistant side panels, and is wrapped vertically with one or more explosion resistant sheets to form a plurality of the explosion resistant side panels. One or more vertically wrapped explosion resistant sheets are currently preferably connected to one or more other explosion resistant sheets that extend along the bottom panel. The explosion resistant sheets are typically wider than the container, so that they are cut with notches at the corners, and overlap.
In a presently preferred aspect of the invention, the explosion resistant panels comprise a plurality of layers of explosion resistant sheets. The explosion resistant panels may also include a sheet of polycarbonate, and may also include padding or insulation placed between layers of the explosion resistant sheets. In another currently preferred aspect of the invention, the side panels and flexible door comprise a plurality of explosion resistant sheets, and at least one of the explosion resistant sheets of the plurality of explosion resistant sheets have edges wrapped around and secured to one or more mounting strips, with the edges of the plurality of explosion resistant sheets and the one or more one mounting strips being bonded together. The edges of the plurality of explosion resistant sheets and the one or more mounting strips are currently preferably bonded together by at least one layer of adhesive film, which can comprise a thermoplastic polymer, such as a semi-crystalline thermoplastic polymer, and is currently preferably a thermoplastic ionomer. Alternatively, the edges of the plurality of explosion resistant sheets and the one or more mounting strips can be bonded together by a coating of a bonding resin, such as epoxy resin.
In a currently preferred embodiment, each explosion resistant sheet comprises at least two layers of explosion resistant material, with at least two of the layers having edges around and secured to first and second mounting strips. In a presently preferred aspect, the edges of at least one layer of the explosion resistant sheets are bonded to the main body of the layers and to the metal strip by at least one layer of film adhesive. In another presently preferred aspect, one or more additional layers of explosion resistant material can be bonded by at least one layer of film adhesive to at least one layer of explosion resistant material bonded to a mounting strip.
In one presently preferred embodiment, the explosion resistant side panels comprise first and second explosion resistant sheets, an edge of the first explosion resistant sheet being wrapped around and secured to a first mounting strip, and an edge of the second explosion resistant sheet being wrapped around and secured to a second mounting strip, the edges of the first and second explosion resistant sheets and the first and second mounting strips being bonded together.
In an alternative preferred embodiment, the side panels comprise three explosion resistant sheets, an edge of the first explosion resistant sheet being wrapped around and secured to a first mounting strip, and an edge of the second explosion resistant sheet being wrapped around and secured to a second mounting strip, the edges of the first and second explosion resistant sheets and the first and second mounting strips being bonded together, with an edge of the third explosion resistant sheet being bonded between the first explosion resistant sheet and the second explosion resistant sheet.
In another alternative preferred embodiment, the side panels comprise four explosion resistant sheets, an edge of the first explosion resistant sheet being wrapped around and secured to a first mounting strip, and an edge of the second explosion resistant sheet being wrapped around and secured to a second mounting strip, the edges of the first and second explosion resistant sheets and the first and second mounting strips being bonded together, with edges of the third and fourth explosion resistant sheet being bonded between the first explosion resistant sheet and the second explosion resistant sheet.
In yet another presently preferred embodiment, the side panels comprise five explosion resistant sheets, an edge of the first explosion resistant sheet being wrapped around and secured to a first mounting strip, and an edge of the second explosion resistant sheet being wrapped around and secured to a second mounting strip, and the edges of the first and second explosion resistant sheets and the first and second mounting strips being bonded together with edges of the third, fourth and fifth explosion resistant sheet being bonded between the first explosion resistant sheet and the second explosion resistant sheet. The mounting strips are currently preferably formed of metal, such as aluminum.
The flexible door of the explosion resistant cargo container is also preferably formed of one or more explosion resistant sheets of explosion resistant, flexible, high tensile strength material, with the one or more explosion resistant sheets having edges that are each wrapped around and secured to a mounting strip, and door hooks mounted to the one or more explosion resistant sheets and the mounting strip along the side edges of the flexible door. In one presently preferred embodiment, the frame assembly comprises door frame members on either side of the door, with door frame hooks mounted to the door frame members corresponding to the door hooks, such that when the door hooks are interfitted with the door frame hooks on either side of the flexible door, blast pressure from an explosion within the container will cause the connection of the door hooks and door frame hooks to tighten. A strap is also preferably provided for securing the flexible door to the side walls of the cargo container when little or no tension operates to otherwise maintain the connection of the door hooks and door frame hooks.
The bottom explosion resistant panel typically preferably comprises an aluminum plate, and the explosion resistant sheets typically comprise a fabric formed from aramid fibers, although the explosion resistant sheets may also be formed from other explosion resistant, flexible, high tensile strength material such as a fabric formed from fiberglass.
These and other aspects and advantages of the invention will become apparent from the following detailed description and the accompanying drawings, which illustrate by way of example the features of the invention.